<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    <!--    1.更新变量-->
    var myname = "gtt";
    myname = "lms";
    console.log(myname)
    //    声明多个变量
    var age = 18, address = "guangzhou", gz = 2000
    console.log(age, address, gz)
    //    特殊情况
    //     1.只声明不赋值
    var hisname   // underfined
    console.log(hisname)
    // 2.只声明不赋值是可以的
    tel = 110
    console.log(tel)
</script>
</body>
</html>